They are warnings from pylint.
You can tell pylint to ignore that error by create file .pylintrc in your folder
Walkthrough (Ubuntu, working on 19.10 developer version)
How to configure VSCode to compile and run CS50's C code?
1/ Choose a folder like home/user/MOOCs/Harvard/C/
Where you will save all of your c files
2/ Download CS50 library into that directory
Open terminal and go to the path home/user/MOOCs/Harvard/C/ for instance